Hecht



Marh 31, 1964 H. HEcHT 3,126,769

MECHANICAL PRESS Filed May l5, 1961 3 Sheets-Sheet 1 lIilvIl /Nv 15A/TapHELMl/ HECHT 3M.: 1,2/1 My @WMA March 31, 1964 H. HEcHT MECHANICAL PRESS3 Sheets-Sheet 2 Filed May l5 1961 Fig. 3

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MECHANICAL PRESS Filed May l5, 1961 Fig. 4

3 Sheets-Sheet 3 United States Patent 3,126,769 MECHANlCAL PRESS HelmutHecht, Goppingen, Germany, assigner to MAY- Pressenbau Ltd., SchwabischGmuntl, Germany Filed May 15, 1961, Ser. No. 110,200 3 Claims. (Cl.78-39) The present invention relates to a mechanical press having atable, which is preferably stationary, and a reciprocating ram operatedby a crank or eccentric.

In quite a number of operations, for example in the cold deforming ofmetal it is unfavorable if the ram reciprocated by the crank oreccentric acts on the work piece treated as it were with a blow. On thecontrary it is particularly advantageous in many cases, when thepressure applied by the ram after its impact on the Work piece increasescomparatively slowly to a maximum so that the material of the work piecehas sufficient time for being deformed. In order to achieve this it hashitherto been of advantage to use for certain operations hydraulicpresses, which make a less hard impact on the work piece and thepressure of which is controllable. On the other hand it has not beenpossible hitherto to develop mechanical presses in a manner favorablefor these operations.

The present invention has the principal object of providing mechanicalpresses, for example crankor eccentric-presses, the pressure of Whoserams applied to the work pieces upon impact is smaller than the endpressure.

With this and other objects in view which will become apparent laterfrom this specification and the accompanying drawings I provide amechanical press comprising in combination: a table, a drive, a ramoperatively connected to said drive and in operation reciprocated bysaid drive relative to said table, a presser member mounted in said ramopposite said table movably relative to said ram in the axial directionof the latter, abutments arranged on said ram limiting the movement ofsaid presser member relative to said ram to a pre-determined length ineither direction, hydraulic pressure fluid in operation contained in ahydraulic pressure chamber enclosed between the said ram and the saidpresser member resisting the receding of said pressure member into saidram under the reaction of the pressing force applied by said pressermember to a work piece resting against said table, and restoring thesaid presser member to its starting position upon said pressing forceceasing to act.

rl`his arrangement acts as a damping device, by which the pressure uponimpact of the ram on the work piece is reduced to a minimum andgradually increases to a predetermined value, so that the pressureapplied to the Work piece is not a hard blow but comparatively soft.Consequently the material to be deformed is not set in motion suddenly,but in a desirable manner gradually, whereby a more favorable andfaultless ilow of the material is achieved.

The arrangement may be made in such a manner that the reaction of thepressure Huid during the receding of the presser member under thepressing force is progressively increased by a control means, preferablyup to the magnitude of the pressing force itself. This may for examplebe attained in that the pressure iluid displaced is forced through athrottle member, for example one or more restricted passages.

A particularly simple and reliable construction is achieved, when thecontrol means has a passage the area of which gradually diminishes asthe presser member recedes, namely if desired so far that this passageis completely or almost completely closed in the retracted end positionof the said presser member. In this case the final maximum pressure ofthe ram is attained at the end of the receding movement of the pressermember.

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The control of the through-flow passage may for example be effected by acontrol element having the form of a projection matching the shape ofthe through-how passage and attached to the end face of the pressermember averted from the table. The shape of this projection dependsaccordingly on the shape of the through-flow passage. For example onecomponent defining the through-low passage may be conical, and then thesaid projection has likewise conveniently a conical shape. By suitablyshaping the through-How passage and the control element the pressurerise upon the receding of the presser member may in any case beinfluenced in a predetermined manner.

As a pressure fluid preferably a liquid is used, which acts directly onthe presser member and flows through the control means, which liquid issubject to a gaseous pressure medium, so that similar to a liquidaccumulator a movement of the liquid is possible either under theiniluence, or against the action, of the compressed gas, respectively.

Conveniently moreover a through-flow adjustment member operable fromoutside is provided on the ram by the aid of which the effectivethrough-flow area is adjustable.

In order to vary the damping of the presser member attainable by theinvention within wide limits it is convenient to provide, parallel tothe main through-flow passage controlled by the presser member, at leastone by-pass or secondary passage the area of which is adjustable bymeans of a throttle valve operable preferably from outside. By suitablechoice of the cross section area of this by-pass it may for example beattained that the damping is a minimum when said by-pass is completelyopen since in this case practically the throughflow of the liquidthrough the main through-flow passage is no longer decisive, since theliquid can flow olf through the by-pass without difficulty, and thedamping is in this case practically determined exclusively by thepressure of the compressed gas acting on the pressure fluid. By suitableadjustment of the throttle valve the characteristic of damping may bevaried within wide limits in a manner desirable for the workingoperations.

Advantageously several by-passes may be arranged on a pitch circle at anequal angular spacing from one another in order thus to prevent anunequal pressure distribution with respect to the presser member.

lf desired, on the presser member moreover a central member may bearranged, which penetrates through the main through-flow passage, sothat the latter assumes an annular shape. By this arrangement it is madepossible to provide centrally in the ram or presser member,respectively, some auxiliary members such as for example an ejector forejecting the work piece.

These and other features of my said invention will be clearly understoodfrom the following description of an embodiment and a modificationthereof given by Way of example with reference to the accompanyingdrawings, in which:

FIG. l is a front elevation of a first embodiment of a press accordingto the present invention;

FIG. 2 is a side elevation to FIG. l;

FIG. 3 is a part-section on the line 3-3 of FIG. 2 on a larger scale;

FIG. 4 is a part-section corresponding to FIG. 3 of a modifiedembodiment of the present invention.

In the FlGS. 1-3 a press fr-arne is denoted 10' as a whole, which hastwo side portions i111 and 12, and a table 13.

The drive of the press is effected by a drive motor (not shown) througha drive shaft 15 carrying a gear pinion *16 in mesh with a spur gear 17mounted on a lay shaft 18 journalled in the lower portion of frame 16.

The drive shaft .115 is extended through and beyond the lower portion ofthe frame, and carries at its left hand side end in FIG. l a furthergear pinion 2&1 in mesh with a further spur gear Z1 which is likewisekeyed to the lay shaft 18. On the outside of the drive gear 17 and 21,respectively, a crank pin Z7 and 28, respectively, is arranged, on whicha connecting rod 34Bl and 3K1, respectively, is articulated.

The two connecting rods 30 and 31 are arranged at both sides of thetable on the side portions L1 and 12 in such a. manner as to form acrank press having two uprightis and a symmetrical drive on both sides.Above the table in a guide 3S a ram denoted 36 as a whole is slidablymounted, which has a projection 37 on each side (see FIGS. 3 and 4) onwhich an adjustment mechanism is arranged for the `adjustment of theconnecting rods 30 and 311. As will be seen in FIGS. 3 and 4, at each ofthe upper ends of the connecting rods 30 and 31 an adjustment member 40is itted which is screwed into a sleeve 41. This sleeve is mountedrotatable in the projections but is restrained longitudinally, and itsrotation is effected by means of externally rotatable Worms 42 in meshwith Worm wheels arranged on the sleeves 41.

The details of the rst embodiment of the ram according to the inventionwill now be explained in more detail with reference to FIG. 3.

The ram body 50 of the ram 36 is formed partly hollow internally and-has an inner hub-like attachment boss 51 in which a pressure member 52is arranged. The later has a tlange 53- Which is arranged in acorresponding cylindrical recess S4 on the underside of the ram body Sand can move therein in the axial direction a predetermined path, theupper abutment of this movement being formed by the end face 55 of saidcylindrical recess 54, and the 4lower abutment by the head S6 of atleast one screw 57 iixed in the ram body. As Will be seen in FIG. 3, thepresser member S2 may accordingly move a predetermined path a in theaxial direction.

The presser member 52 has an inner cylindrical recess 6i) serving forthe attachment of tools. This recess is closed on top by a closure piece61.

On the attachment boss :1 a cylindrical extension piece 62 is attached,which is sealed against the presser member 52 by the aid of gland rings63. Between the upper end face of the closure piece 61 and the underside65 of the extension piece 62 a cylindrical cavity 66 is ormed, the axialheight of which exceeds the path a.

The closure piece 61 carries in the middle a frustoconical control pin68, which co-operates wih a conical portion 69 of a through-How passage649/70, which includes moreover a cylindrical portion '70. On theextension piece 6-2 a cover '7K4 is arranged in such a manner thatbetween the underside of the cover 74 and the face 75 of the extensionpiece 62 a cavity 76 is formed, which is in communication throughconnecting line 77 with a pressure vessel 78 to which a source ofcompressed gas (not shown in the drawing) is connected by means of aconnector 79.

In the cover 74 moreover a control member l82` is provided in the formof an axially adjustable screw, which at its lower end has a conicalcontrol head '83 co-operating with the cylindrical portion 70 of thethrough-110W passage 69, 70.

The manner ci functioning of the device described is as follows:

In a state of rest the presser member is in the position shown in FIG. 3and accordingly contacts lthe abutment screw 57. Then the cavity 66 isentirely and the cavity 76 is partly filled with liquid, namely thelatter up to a liqfuid level denoted 84. The compressed air contained inthe pressure vessel 78 acts on this level so that under Vthis action theliquid serving as the transmission medium constantly tends to move thepresser member 52 into its lower position illustrated in FIG. 3.

When in the pressing operation a pressure is applied on the lower end'face ci the pressure member in the upward direction the presser memberis moved upward relative to the ram body 5i) at a certain pressureexceeding the pressure of the compressed air, and thereby the liquidcontained in the space `66 is forced through the passage 69, 7i), whichduring the upward movement of the presser member is progressivelyreduced by the cooperation of the control pin v68 with the passage 69',70, so that the pressure required for forcing the liquid through saidpassage progressively increases. In the uppermost position oi thepresser member, i.e. when the same has moved axially upward the amounta, the passage is completely or nearly .completely closed, and in thisposition the presser member 52 is carried along immediately by the bodySti, i.e. at this moment the action of the slidably proper member iscompletely abolished.

In FIG. 4 a second embodiment of the device according to the inventionis illustrated.

Likewise in a ram body here a presser member 86 is so arranged, that thelatter may move a predetermined length a relative to the ram body. Thepresser member 86 is closed by a closure member 87 on which a centralmember 8S is attached which penetrates through this closure member. Thiscentral member has a conical control collar 89 which cor-operates with acorresponding conical portion 90 of an annular extension 91 of the rambody.

The ram body is closed on top by a cover 92 through which penetrates thesaid central member 88 and which is sealed against this central memberby means of a gland 93.

`On the lower end of the central member S8 a lock mit 1101 is screwedwhereby the contical control collar 89 is iirmly pressed against theclosure member 87. On the upper end of the central member `88 a lock nut102 is screwed. This nut 1012 can rest on a cover plate i103 inserted inthe cover 92.

In the aforesaid cover 92 an adjustment screw '94 is provided, which atits lower end (FIG. 4) is provided with a valve cone 95 cooperating witha valve seat 96 by a by-pass duct 97, which connects the chamber 98 withthe `chamber 99. Glands 104 on the closure member 87 seal the same ofiagainst the chamber 98.

The by-pass duct 97 maybe varied in its effective crosssection area atwill by adjusting the adjustment screw 94, in order to influence thedamping characteristics of the damping device in the manner desired.

While I have described herein and illustrated in the accompanyingdrawing what may be considered a typical and particularly usefulembodiment of my said invention I Wish it to be understood that I do notlimit myself to the particular details and dimensions described andillustrated; for obvious modifications will occur to a person skilled inthe art.

What -I claim as my invention and desire to secure by Letters Patent is:

1. A mechanical press comprising a press ram having a recess, means forreciprocating said press ram in an axial direction, a piston located insaid recess axially movable relative to said press ram from an:inoperative to an operating position leaving exposed a partial volume ofsaid recess, a lfirst stop means limiting the movement of said piston insaid recess when in inoperative position, a second stop means limitingthe movement of said piston in lsaid recess ywhen in operating position,said ram having a cavity containing a liquid under pressure, ya passageconnecting said partial volume and said cavity in said inoperativeposition of said piston, said passage inclnding a part extending in saidaxial direction, the width of said part gradually diminishing in thedirection of movement of said piston from said inoperative position tosaid operating position, throttling means rigidly ixed to said pistonand in said inoperative position of said piston extending with lateralclearance into said part of said passage, said clearance being graduallyreduced upon movement of said piston from` said inoperative position tosaid operating position to increase the action of said throttling means.

2. A mechanical press comprising a press ram having a recess, means forreciprocating said press ram in an axial direction, a piston located insaid recess axially movable relative to said press ram from aninoperative to an operating position leaving exposed a partial volume ofsaid recess, a lirst stop means limiting the movement of lsaid piston insaid recess When in inoperative position, a second stop means limitingthe movement of said piston in said recess when in operating position,said ram having a cavity containing a liquid under pressure, a passageconnecting said partial volume and said cavity in said inoperativeposition of said piston, said passage including a part extending in saidaxial direction, the Width of said part gradually diminishing in thedirection of movement of said piston from said inoperative position tosaid operating position, throttling means rigidly fixed to said pistonand in said inoperative position of said piston extending with lateralclearance into said part of said passage, said clearance being graduallyreduced upon movement of said piston from said inoperative position tosaid operating position to increase the action of said throttlingme-ans, said partial volume, said passage and said cavity containing aliquid forming a level of liquid in said cavity, and supply means forpneumatic pressure connected to said cavity to resiliently 'charge saidlevel of liquid by said pneumatic pressure.

3. A mechanical press comprising a press ram having a recess, means forreciprocating said press ram in an axial direction, a partition in saidfram dividing said recess into a first and a second pressure chamber, acylindrical tool support in said lirst chamber axially movable relativeto said press ram from an inoperative to an operating position, sealingmeans upon said tool support cooperating with the wall of said firstpressure chamber to seal the latter when said tool support is movedrelative to said ram, -a rst stop means limiting the movement of saidtool support in said ram when in inoperative position, a second stopmeans limiting the movement of said tool support in said ram when inoperating position, a passage connecting said two chambers in saidinoperative position, said passage including a part extending in saidaxial direction, the Width of said part gradually diminishing in thedirection of movement of said piston from said inoperative position tosaid operating position, throttling means rigidly xed to said piston andin said inoperative position `of said piston extending with lateralclearance into said part of said passage, said clearance being`gradually reduced rupon movement of said piston from said inoperativeposition to said operating position to increase the action of saidthrottling means, said chambers and said passage containing a liquidforming a level of liquid in said second pressure chamber, and pneumaticpressure supply means connected to said second pressure chamber toresiliently charge said level of liquid by said pneumatic pressure.

References Cited in the lile of this patent UNITED STATES PATENTS933,010 Wilzin Aug. y31, 1909 1,780,531 Messier Nov. 4, 1930 2,007,290Treer lJ'uly 9, 1935 2,164,640 Cannon July 9, 1939 2,333,529 Ernst Nov.2, 1943 '2,482,280 Lerma Sept. 20, 1949 2,924,446 Williamson Feb. 9,1960

1. A MECHANICAL PRESS COMPRISING A PRESS RAM HAVING A RECESS, MEANS FORRECIPROCATING SAID PRESS RAM IN AN AXIAL DIRECTION, A PISTON LOCATED INSAID RECESS AXIALLY MOVABLE RELATIVE TO SAID PRESS RAM FROM ANINOPERATIVE TO AN OPERATING POSITION LEAVING EXPOSED A PARTIAL VOLUME OFSAID RECESS, A FIRST STOP MEANS LIMITING THE MOVEMENT OF SAID PISTON INSAID RECESS WHEN IN INOPERATIVE POSITION, A SECOND STOP MEANS LIMITINGTHE MOVEMENT OF SAID PISTON IN SAID RECESS WHEN IN OPERATING POSITION,SAID RAM HAVING A CAVITY CONTAINING A LIQUID UNDER PRESSURE, A PASSAGECONNECTING SAID PARTIAL VOLUME AND SAID CAVITY IN SAID INOPERATIVEPOSITION OF SAID PISTON, SAID PASSAGE IN-